Abstract

The mechanism of molecular interaction between β-lactoglobulin (β-lg) and sorghum bran phenolic compounds from 4 genotypes was studied. Catechin (CA) and ferulic acid (FA) were used as model systems. Higher affinity for β-lg:FA interaction (Ksv ≈ 105 M−1) compared with β-lg:CA interaction (Ksv ≈ 104 M−1) was revealed, with different preferable binding sites identified through molecular docking. Nevertheless, regarding the molecular interaction between the proteins and the complex extracts of phenolic compounds, Ksv in the magnitude order of 104 M−1 were observed. Antioxidant capacity progressively increased after protein-phenolic interaction, indicating a potential synergistic effect. Concerning the thermal stability of the phenolic compounds, epimerization as the primary response of CA to thermal treatment (90 °C / 10 min) was identified, but the addition of β-lg exerted a protective effect against CA degradation (−7 % in β-lg:CA complexes); however, proteins were not able to protect complex phenolic matrices (e.g. sorghum extracts).

Abstract

Despite the growing market for plant-based products, rarely a single plant protein source manages to provide all the essential amino acids in a balanced way. Mixed protein systems combining proteins from more than one plant source may be useful to overcome this drawback. However, the mixture of proteins from different plant sources may impact the technological performance of the system. In this context, the influence of heat treatments of 75 and 95 °C for 15 min at neutral pH on the colloidal and the techno-functional properties of mixtures of protein isolates from lentil and oat (LO) and from faba bean and oat (FO) were investigated. The applied heat treatments induced subtle changes in the colloidal properties of the different systems. It was evidenced by size exclusion chromatography that oat proteins were more prone to heat induced changes than lentil or faba bean proteins. Regarding the techno-functional properties, mixing the proteins from the different sources had an antagonistic effect on foamability. On the other hand, an additive effect was observed for emulsifying capacities, with legume proteins displaying values between 93 and 100%, oat proteins close to 65%, and mixed systems between 78 and 93 %. Vicilin (7S) and β-basic subunits of legumin (11S) from lentil and faba bean, and oat 12S globulin were the main protein fractions stabilizing the interface of the obtained emulsions. The proteins from both sources coexisted at the interface of the emulsions stabilized by the mixed systems. The microstructure of the thermo-induced gels was dictated by oat proteins. However, the different legumes played a determining role in the critical gelling concentration measured (8 % w/w and 11.5 % w/w respectively for LO and FO). Mixing oat proteins with lentil or faba bean proteins allows modulating the techno-functional performance of the systems, thus represents an opportunity for innovative applications.

Abstract

In recent years, much has been discussed about the use of edible insects as an alternative source of protein. Rearing insects require less use of land and water, as well as generate fewer greenhouse gases compared with conventional livestock. In this scenario, research has been carried out to explore the use of insect proteins as food ingredients since the decharacterization of insects increases their acceptance by consumers. Insect proteins display interesting technofunctional properties, such as the ability to form and stabilize emulsions, foams, and gels. Moreover, some studies already used insect proteins or insect flours to partially replace conventional ingredients in food formulations, mainly in bakery and meat analog products, obtaining promising results. However, to validate edible insects as a food ingredient, some challenges need to be overcome, such as the implementation of new regulations, increasing consumer acceptance, a better understanding of allergenic risks and toxicity, and using viable unit operations to scale up the production of protein-rich insect ingredients at an industrial level.

Abstract

Delivery systems designed through protein stabilized emulsions are promising for incorporating carotenoids in different products. Nevertheless, the versatility in structures of such systems raises questions regarding the effect of the bioactive compound localization on their bio-efficacy, in particular for double emulsions. In this context, the aims of this study were to determine the impact of the localization of lutein in different water/oil/water double emulsions versus a single oil/water emulsion on the stability and in vitro bioaccessibility of lutein, a lipophilic carotenoid. The inner aqueous phase, which contained whey protein isolate (WPI) nanoparticles obtained by desolvation, was emulsified in sunflower oil stabilized by polyglycerol polyricinoleate (PGPR). The primary emulsion was then emulsified in a continuous aqueous phase containing whey protein isolate (WPI) and xanthan gum, the latter to increase the viscosity of the outer phase and delay creaming. Lutein was incorporated using different strategies: (1) lutein entrapped by WPI nanoparticles within the inner water phase of a double emulsion (W-L/O/W); (2) lutein incorporated into the oil phase of the double emulsion (W/O-L/W); (3) lutein incorporated in the oil phase of a single emulsion (O-L/W). All systems contained similar whey protein concentrations, as well as all other stabilizers. W-L/O/W sample showed the lowest lutein stability against light exposure during storage, and the highest lutein bioaccessibility after in vitro digestion, for freshly made samples. Furthermore, the in vitro bioaccessibility of lutein incorporated into the single emulsion was considerably lower than those observed for the double emulsions. The results reinforce the importance of designing appropriate structures for delivering improved stability and bioaccessibility of bioactive compounds.

Abstract

The interaction between whey proteins and carotenoid is reported to improve carotenoid solubility and stability, however, the strong trend of carotenoids to aggregate when in polar systems is often neglected in papers addressing their molecular interaction. Therefore, this study focused on characterizing the aggregative behavior of the carotenoids from yellow mombin (Spondias mombin) and to understand how these carotenoids behave when added to aqueous dispersions of whey proteins. Carotenoids-rich extract, containing mainly β-cryptoxanthin and lutein, was obtained from freeze-dried yellow mombin pulp and its aggregative behavior in ethanol/water medium was studied. By increasing the medium polarity, carotenoids trend to form J-aggregation, causing a drop in the color intensity of the solution. When added to whey protein aqueous dispersions, rather than a protein-carotenoid bimolecular interaction, the formation of co-aggregates between carotenoids and whey proteins was evidenced by preparative size exclusion chromatography. These results may contribute to the developing functional food products.

Abstract

Consumer demand for UHT high-protein dairy beverages is growing all around the world. To overcome the potential low stability of these products during processing and storage remains a great challenge for dairy industries. In this context, the potential of preheating treatment coupled with homogenisation or the addition of sucrose or corn soluble fibre on reducing the sedimentation level of UHT dairy beverages containing 10% w/w of protein and equivalent proportion of caseins to whey proteins were evaluated. The samples supplemented with sucrose or corn soluble fibre displayed a reduced overall particle size distribution, but equivalent amount of sediment compared with that in the control sample. The applied pretreatment promoted intense whey protein denaturation and reduced the overall particle size distribution and the amount of material sedimented compared with the control sample. The applied pretreatment has potential to improve the stability of UHT high-protein dairy beverages.

Abstract

Considering that carotenoids are found acylated to fatty acids in most edible fruits, the influence of the ratio of free to acylated lutein on the hydrolysis extent and bioaccessibility was evaluated by in vitro digestion. For this purpose, for the first time, esterified, free, or a mixture of both carotenoid forms was used in the lipid phase of emulsions stabilized by sodium caseinate (NaCas) and native phosphocaseinate (PPCN). Marigold petals was used as a source of lutein-rich extracts. The emulsions were characterized and the extent of ester hydrolysis, carotenoid recovery, and bioaccessibility were evaluated by LC-DAD-MS/MS. Besides low polydispersity, NaCas and PPCN stabilized emulsions exhibited a constant mean droplet diameter of about 260 and 330 nm, respectively, after 7 days. Caseins were completely digested after the gastric digestion step. Moreover, casein supramolecular structure did not significantly affect carotenoid bioaccessibility. Lutein was majorly found in its free form in all bioaccessible fractions. The carotenoid bioaccessibility increased from 3% to 40% by increasing the percentage of free carotenoids from 0.5 to 100% in the emulsions; but the carotenoid recovery and hydrolysis extent of lutein esters were not affected. In conclusion, emulsion-based systems for carotenoid delivery stabilized either by NaCas or PPCN provided similar carotenoid bioaccessibility. Furthermore, bioaccessibility was inversely dependent on the overall hydrophobicity of the carotenoid extract. Our results suggest that the low bioaccessibility of esterified carotenoids was a consequence of their limited hydrolysis extent. This study provides information that may help design emulsion-based systems stabilized by food protein as a vehicle for carotenoids.

Abstract

Most infant formulas (IFs) use cow's milk-based ingredients as raw material. Nevertheless, to produce IFs for special needs, these raw materials may be replaced by other ones from different protein sources such as soy and rice. During transport and storage, IFs can be subjected to high temperatures, then, several physicochemical alterations may be accelerated. Even so, little is known about how the composition of IFs containing different protein sources may modulate their aging. Therefore, the objective of this work was to compare how different physicochemical parameters of IFs containing cow's milk, soy, or rice as major protein sources evolved during aging under different temperatures. Mild storage temperatures (3 °C and 25 °C) promoted little changes in the evaluated parameters. However, critical storage temperature (50 °C) (i) favored the faster development of the Maillard reaction in milk-IF and soy-IF; (ii) impaired their rehydration ability and (iii) favored the increase in the free fat content of rice-IF and soy-IF. This work is relevant in establishing parallels between different infant formulas that aim to meet the same nutritional demands of infants.

Abstract

We are experiencing an increase in the availability of protein ingredients from more sustainable production sources, and we need to learn how to utilize them to create highly nutritional and climate friendly foods. Much work is needed to assist in innovation, by developing principles leading to the design of the best structures to ensure optimal function. We propose a holistic approach to the design of new sustainable proteins for food, so that they may compare favorably to their animal sourced counterparts. While the immediate challenges are related to improving processing functionality and providing the essential amino acids balance, we will soon also need to learn to pay close attention to the molecular interactions occurring during processing, as these can be modulated to form different supramolecular structures. This shift will create new opportunities to innovate and create a new generation of highly nutritious and functional foods. This review focuses on the recent trends on the use of plant protein blends, and highlights the research gaps and challenges related to using ingredients of different composition and history to develop more climate friendly foods.

Abstract

Background

Caseins and whey proteins have great potential for interacting with carotenoids due to their binding sites with hydrophobic domains. Even if a neglected amount of carotenoids is naturally bound to milk proteins, the complexation of these molecules has been proven to be an efficient approach for increasing carotenoid solubility and protection against oxidation, for instance.

Scope and approach

This review compiled the updated research progress in this field, pointing out all the benefits associated with the interaction between carotenoids and milk proteins and the challenges of characterizing the mechanisms involved in the binding. The impact of temperature, pH, and ionic strength, and the intrinsic characteristics of milk proteins and carotenoids on their binding affinity were reviewed. The main analytical methods applied for the characterization of the binding mechanism were comparatively discussed.

Key findings and conclusions

The binding of carotenoids to milk proteins is a promising strategy for the development of functional fat-free foods enriched with these bioactive molecules. However, the practical challenges to investigate the interaction between milk proteins and this low-water soluble group of molecules must be considered. Despite being affected by many factors, a binding constant of about 104 M−1 and moderate affinity between carotenoids and milk proteins were frequently reported. Finally, promising techniques and future challenges for this scientific field were addressed. Besides research groups focused on elucidating the mechanism behind the binding between carotenoids and proteins, the scope covered by this review may also interest those involved in the development of healthier formulated food products.

Abstract

Dry heating (DH) in an alkaline environment has been proposed as a treatment that can improve some techno-functional properties of whey proteins, such as their water-holding capacity and gelling properties. Nevertheless, information concerning the impact of DH in an alkaline environment on the foaming properties of whey proteins is not available in the literature. In this context, lyophilized whey protein isolate (WPI) powders with and without added lactose were submitted to DH treatments (60 and 80 °C) under neutral and alkaline environments for 48 h. Even without DH, the alkaline environment induced the formation of insoluble protein aggregates stabilized by disulfide and non-disulfide covalent interactions. The amount of insoluble protein aggregates enhanced with the increase in the intensity of DH. No insoluble aggregates were observed for samples produced in a neutral environment. Furthermore, no difference in the apparent secondary structure of the proteins in the soluble fraction of neutral or alkaline equivalent samples could be evidenced. In addition, the intensity of the population of soluble protein aggregates rose by increasing the intensity of DH treatment; however, it was comparable between neutral and alkaline equivalent samples. DH in an alkaline environment at 80 °C for 48 h significantly enhanced the stability of the foams produced by the soluble fraction of lactose-added samples, corroborating its potential to improve useful techno-functional properties of whey proteins. 

Abstract

Background

Milk and dairy products are among the most important protein sources for humans. During the processing of these products, applied thermal treatments often induce changes in the proteins’ structure and consequently their techno-functionalities. Nevertheless, because of the increasing consumer demand for high-quality food products, considerable research has been completed focusing on minimal processing using emerging technologies. However, knowledge concerning how these emerging technologies affect milk proteins is diffuse.

Scope and approach

The impacts of emerging technologies on the structure and techno-functionalities of caseins and whey proteins are compared to the impacts caused by thermal treatments in this review. The main emerging technologies discussed are ultrasound, high-pressure treatment, pulsed electric fields, microwave, radio frequency, irradiation, and supercritical fluid extrusion. Structural changes induced by these technologies and by consequent changes in solubility, gelling capacity, interfacial activity, binding properties and allergenicity of milk proteins were highlighted.

Key findings and conclusions

Even if intense treatments negatively affect milk proteins’ techno-functional properties, these properties may be improved by controlling the induced structural changes. Because of the diversity of technologies, several different structural effects may be expected. Thus, this review may be beneficial to identify suitable processing conditions for the development of innovative dairy products/ingredients. Future challenges for this scientific field are also addressed.